[Client] Feat: Implement MCP client component

composer.json

@@ -26,24 +26,26 @@
     "psr/clock": "^1.0",
     "psr/container": "^2.0",
     "psr/event-dispatcher": "^1.0",
+    "psr/http-client": "^1.0",
     "psr/http-factory": "^1.1",
     "psr/http-message": "^2.0",
     "psr/log": "^1.0 || ^2.0 || ^3.0",
     "symfony/finder": "^6.4 || ^7.3 || ^8.0",
     "symfony/uid": "^6.4 || ^7.3 || ^8.0"
   },
   "require-dev": {
+    "laminas/laminas-httphandlerrunner": "^2.12",
+    "nyholm/psr7": "^1.8",
+    "nyholm/psr7-server": "^1.1",
     "php-cs-fixer/shim": "^3.91",
     "phpstan/phpstan": "^2.1",
     "phpunit/phpunit": "^10.5",
     "psr/cache": "^3.0",
     "psr/simple-cache": "^3.0",
     "symfony/cache": "^6.4 || ^7.3 || ^8.0",
     "symfony/console": "^6.4 || ^7.3 || ^8.0",
-    "symfony/process": "^6.4 || ^7.3 || ^8.0",
-    "nyholm/psr7": "^1.8",
-    "nyholm/psr7-server": "^1.1",
-    "laminas/laminas-httphandlerrunner": "^2.12"
+    "symfony/http-client": "^7.4",
+    "symfony/process": "^6.4 || ^7.3 || ^8.0"
   },
   "autoload": {
     "psr-4": {
@@ -52,18 +54,18 @@
   },
   "autoload-dev": {
     "psr-4": {
-      "Mcp\\Example\\CachedDiscovery\\": "examples/cached-discovery/",
-      "Mcp\\Example\\ClientCommunication\\": "examples/client-communication/",
-      "Mcp\\Example\\CombinedRegistration\\": "examples/combined-registration/",
-      "Mcp\\Example\\ComplexToolSchema\\": "examples/complex-tool-schema/",
-      "Mcp\\Example\\CustomDependencies\\": "examples/custom-dependencies/",
-      "Mcp\\Example\\CustomMethodHandlers\\": "examples/custom-method-handlers/",
-      "Mcp\\Example\\DiscoveryCalculator\\": "examples/discovery-calculator/",
-      "Mcp\\Example\\DiscoveryUserProfile\\": "examples/discovery-userprofile/",
-      "Mcp\\Example\\EnvVariables\\": "examples/env-variables/",
-      "Mcp\\Example\\ExplicitRegistration\\": "examples/explicit-registration/",
-      "Mcp\\Example\\SchemaShowcase\\": "examples/schema-showcase/",
-      "Mcp\\Example\\ClientLogging\\": "examples/client-logging/",
+      "Mcp\\Example\\Server\\CachedDiscovery\\": "examples/server/cached-discovery/",
+      "Mcp\\Example\\Server\\ClientCommunication\\": "examples/server/client-communication/",
+      "Mcp\\Example\\Server\\CombinedRegistration\\": "examples/server/combined-registration/",
+      "Mcp\\Example\\Server\\ComplexToolSchema\\": "examples/server/complex-tool-schema/",
+      "Mcp\\Example\\Server\\CustomDependencies\\": "examples/server/custom-dependencies/",
+      "Mcp\\Example\\Server\\CustomMethodHandlers\\": "examples/server/custom-method-handlers/",
+      "Mcp\\Example\\Server\\DiscoveryCalculator\\": "examples/server/discovery-calculator/",
+      "Mcp\\Example\\Server\\DiscoveryUserProfile\\": "examples/server/discovery-userprofile/",
+      "Mcp\\Example\\Server\\EnvVariables\\": "examples/server/env-variables/",
+      "Mcp\\Example\\Server\\ExplicitRegistration\\": "examples/server/explicit-registration/",
+      "Mcp\\Example\\Server\\SchemaShowcase\\": "examples/server/schema-showcase/",
+      "Mcp\\Example\\Server\\ClientLogging\\": "examples/server/client-logging/",
       "Mcp\\Tests\\": "tests/"
     }
   },
@@ -73,4 +75,4 @@
       "php-http/discovery": false
     }
   }
-}
+}

examples/client/README.md

@@ -0,0 +1,27 @@
+# Client Examples
+
+These examples demonstrate how to use the MCP PHP Client SDK.
+
+## STDIO Client
+
+Connects to an MCP server running as a child process:
+
+```bash
+php examples/client/stdio_discovery_calculator.php
+```
+
+## HTTP Client
+
+Connects to an MCP server over HTTP:
+
+```bash
+# First, start an HTTP server
+php -S localhost:8080 examples/http-discovery-userprofile/server.php
+
+# Then run the client
+php examples/client/http_discovery_userprofile.php
+```
+
+## Requirements
+
+All examples require the server examples to be available. The STDIO examples spawn the server process, while the HTTP examples connect to a running HTTP server.

examples/client/http_client_communication.php

@@ -0,0 +1,122 @@
+<?php
+
+/**
+ * HTTP Client Communication Example
+ *
+ * This example demonstrates server-to-client communication over HTTP:
+ * - Logging notifications
+ * - Progress notifications (via SSE streaming)
+ * - Sampling requests (mocked LLM response)
+ *
+ * Usage:
+ *   1. Start the server: php -S 127.0.0.1:8000 examples/server/client-communication/server.php
+ *   2. Run this script: php examples/client/http_client_communication.php
+ *
+ * Note: PHP's built-in server works for listing tools, calling tools, and receiving
+ * progress/logging notifications. However, sampling requires a concurrent-capable server
+ * (e.g., Symfony CLI, PHP-FPM) since the server must process the client's sampling
+ * response while the original tool request is still pending. 
+ * 
+ * Eg. symfony serve --passthru=examples/server/client-communication/server.php --no-tls
+ */
+
+declare(strict_types=1);
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+
+use Mcp\Client\Client;
+use Mcp\Client\Handler\LoggingNotificationHandler;
+use Mcp\Client\Handler\SamplingRequestHandler;
+use Mcp\Client\Transport\HttpClientTransport;
+use Mcp\Schema\ClientCapabilities;
+use Mcp\Schema\Content\TextContent;
+use Mcp\Schema\Enum\Role;
+use Mcp\Schema\Notification\LoggingMessageNotification;
+use Mcp\Schema\Request\CreateSamplingMessageRequest;
+use Mcp\Schema\Result\CreateSamplingMessageResult;
+
+$endpoint = 'http://127.0.0.1:8000';
+
+$loggingNotificationHandler = new LoggingNotificationHandler(function (LoggingMessageNotification $n) {
+    echo "[LOG {$n->level->value}] {$n->data}\n";
+});
+
+$samplingRequestHandler = new SamplingRequestHandler(function (CreateSamplingMessageRequest $request): CreateSamplingMessageResult {
+    echo "[SAMPLING] Server requested LLM sampling (max {$request->maxTokens} tokens)\n";
+
+    $mockResponse = "Based on the incident analysis, I recommend: 1) Activate the on-call team, " .
+        "2) Isolate affected systems, 3) Begin root cause analysis, 4) Prepare stakeholder communication.";
+
+    return new CreateSamplingMessageResult(
+        role: Role::Assistant,
+        content: new TextContent($mockResponse),
+        model: 'mock-gpt-4',
+        stopReason: 'end_turn',
+    );
+});
+
+$client = Client::builder()
+    ->setClientInfo('HTTP Client Communication Test', '1.0.0')
+    ->setInitTimeout(30)
+    ->setRequestTimeout(120)
+    ->setCapabilities(new ClientCapabilities(sampling: true))
+    ->addNotificationHandler($loggingNotificationHandler)
+    ->addRequestHandler($samplingRequestHandler)
+    ->build();
+
+$transport = new HttpClientTransport(endpoint: $endpoint);
+
+try {
+    echo "Connecting to MCP server at {$endpoint}...\n";
+    $client->connect($transport);
+
+    $serverInfo = $client->getServerInfo();
+    echo "Connected to: " . ($serverInfo?->name ?? 'unknown') . "\n\n";
+
+    echo "Available tools:\n";
+    $toolsResult = $client->listTools();
+    foreach ($toolsResult->tools as $tool) {
+        echo "  - {$tool->name}\n";
+    }
+    echo "\n";
+
+    echo "Calling 'run_dataset_quality_checks'...\n\n";
+    $result = $client->callTool(
+        name: 'run_dataset_quality_checks',
+        arguments: ['dataset' => 'sales_transactions_q4'],
+        onProgress: function (float $progress, ?float $total, ?string $message) {
+            $percent = $total > 0 ? round(($progress / $total) * 100) : '?';
+            echo "[PROGRESS {$percent}%] {$message}\n";
+        }
+    );
+
+    echo "\nResult:\n";
+    foreach ($result->content as $content) {
+        if ($content instanceof TextContent) {
+            echo $content->text . "\n";
+        }
+    }
+
+    echo "\nCalling 'coordinate_incident_response'...\n\n";
+    $result = $client->callTool(
+        name: 'coordinate_incident_response',
+        arguments: ['incidentTitle' => 'Database connection pool exhausted'],
+        onProgress: function (float $progress, ?float $total, ?string $message) {
+            $percent = $total > 0 ? round(($progress / $total) * 100) : '?';
+            echo "[PROGRESS {$percent}%] {$message}\n";
+        }
+    );
+
+    echo "\nResult:\n";
+    foreach ($result->content as $content) {
+        if ($content instanceof TextContent) {
+            echo $content->text . "\n";
+        }
+    }
+
+} catch (\Throwable $e) {
+    echo "Error: {$e->getMessage()}\n";
+    echo $e->getTraceAsString() . "\n";
+} finally {
+    $client->disconnect();
+}

examples/client/http_discovery_calculator.php

@@ -0,0 +1,69 @@
+<?php
+
+/**
+ * HTTP Client Example
+ *
+ * This example demonstrates how to use the MCP client with an HTTP transport
+ * to communicate with a remote MCP server over HTTP.
+ *
+ * Usage: php examples/client/http_discovery_calculator.php
+ *
+ * Before running, start an HTTP MCP server:
+ *   php -S localhost:8080 examples/server/http-discovery-calculator/server.php
+ */
+
+declare(strict_types=1);
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+
+use Mcp\Client\Client;
+use Mcp\Client\Transport\HttpClientTransport;
+
+$endpoint = 'http://localhost:8000';
+
+$client = Client::builder()
+    ->setClientInfo('HTTP Example Client', '1.0.0')
+    ->setInitTimeout(30)
+    ->setRequestTimeout(60)
+    ->build();
+
+$transport = new HttpClientTransport($endpoint);
+
+try {
+    echo "Connecting to MCP server at {$endpoint}...\n";
+    $client->connect($transport);
+
+    echo "Connected! Server info:\n";
+    $serverInfo = $client->getServerInfo();
+    echo "  Name: " . ($serverInfo?->name ?? 'unknown') . "\n";
+    echo "  Version: " . ($serverInfo?->version ?? 'unknown') . "\n\n";
+
+    echo "Available tools:\n";
+    $toolsResult = $client->listTools();
+    foreach ($toolsResult->tools as $tool) {
+        echo "  - {$tool->name}: {$tool->description}\n";
+    }
+    echo "\n";
+
+    echo "Available resources:\n";
+    $resourcesResult = $client->listResources();
+    foreach ($resourcesResult->resources as $resource) {
+        echo "  - {$resource->uri}: {$resource->name}\n";
+    }
+    echo "\n";
+
+    echo "Available prompts:\n";
+    $promptsResult = $client->listPrompts();
+    foreach ($promptsResult->prompts as $prompt) {
+        echo "  - {$prompt->name}: {$prompt->description}\n";
+    }
+    echo "\n";
+
+} catch (\Throwable $e) {
+    echo "Error: {$e->getMessage()}\n";
+    echo $e->getTraceAsString() . "\n";
+} finally {
+    echo "Disconnecting...\n";
+    $client->disconnect();
+    echo "Done.\n";
+}